After driving on the tires for two winters I can tell you to underglaze several psi. My tears have prematurely worn on the center lines to the winter wear indicators, but the inner and outer tread is deep meaning I need to replace them early. The fronts have worn evenly running 1 or 2 psi under the sticker.
2011 E90 M3 Jet Black/Black
ZPP, ZCP, ZTP, ZCW, 6FL, PDC, shades, 6MT